• The Journal of Korean Physical Therapy
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• v.11 no.1
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• pp.71-77
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• 1999

The purpose of this study was to investigate the changes of muscle power by transcutaneous electrical nerve stimulation(TBNS), low frequency-low intensity(20pps, invisible muscle contraction intensity), low frequency-high intensity(20pps, visible muscle contraction), high frequency-low intensity(100pps, invisible muscle contraction intensity) and high frequency-high intensity(100pps, visible muscle contraction). The results were as follows. 1. Increased muscle power after 30 minutes of treatment by low frequency-low intensity TENS, and post-treatment 30 minutes muscle power were increased more than pre-treatment power(p<0.05). 2. Decreased muscle power after a 30 minute treatment by low frequency-high intensity TENS, and after the 30 minute treatment was terminated muscle power didn't recover to pre-treatment levels. 3. Decreased muscle power after 30 minute treatment by high frequency-low intensity TENS, but post-treatment 30 minute, muscle power didn't recover to pre-treatment levels. 4. The muscle power was remarkably decreased by high frequency-high intensity TENS after 30 minute treatment, in addition treatment terminated after 30minutes didn,t recover to pre-treatment power(p<0.05). 5. Lower frequency-low intensity TENS are good methods for preventing muscle fatigue, buty high intensity (TENS) are increased muscle fatigue. 6. Traditional TENS by high frequency-low intensity is a good method for preventing muscle fatigue.

• Journal of the Ergonomics Society of Korea
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• v.21 no.2
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• pp.25-33
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• 2002

The purpose of study is to investigate the relationship between the trunk muscle fatigue and recovery time during repetitive extension by using a surface electromyogram(EMG). Ten healthy subjects particioated in a simulated lifting task with five levels of recovery time and three levels of sub-maximal contraction. EMG signals of the L1(Lumbar 1st Vertebrae) and L3(Lumbar 3rd Vertebrae) level of the erector spinae muscle were recorded. and analyzed in terms of MPF(mean power frequency) parameter to quantify the level of muscle fatigue. It was found that MPF significantly (p<0.05) decreased during repetitive extension task at 50% and 75% sub-maximal contractions. Then it took minutes for the trunk muscle to recover from fatigue during 50% sub-maximal contraction. and it took five minutes during 75% sub-maximal contraction. and it took five minutes during 75% sub-maximal contraction. The recovery time estimated by the maximum force needs to be re-evaluated for the trunk muscle to fully recover from fatigue. In conclusion. the work/rest cycle needs to be studied based upon the information of muscle fatigue in order to prevent workers from musculoskeletal injuries during repetitive lifting task.

• Smart Structures and Systems
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• v.6 no.9
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• pp.1041-1056
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• 2010

This paper investigates the possibility of a strategy for an automatic full recover of a structural component undergoing loading-unloading (fatigue) cycles: full recover means here that no replacement is required at the end of the mission. The goal is to obtain a material capable of self healing earlier before the damage becomes irreversible. Attention is focused on metallic materials, and in particular on shape memory alloys, for which the recovering policy just relies on thermal treatments. The results of several fatigue tests are first reported to acquire a deep understanding of the physical process. Then, for cycles of constant amplitude, the self-healing objective is achieved by mounting, on the structural component of interest, a suitable microcontroller. Its input, from suitable sensors, covers the current stress and strain in the alloy. The microcontroller elaborates from the input the value of a decisional parameter and activates the thermal process when a threshold is overcome.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.10a
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• pp.721-724
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• 1999

The concrete structure under fatigue load depresses in mechanical capability or breaks down finally because of the fatigue. So recently the study on strengthening methods using bonded plate is widely attended. Which could be constructed under use and without damaging the structure. The intention of this method is to increase the useability of the structure and to recover the strength. So application on fields are sharply increasing. In this study it is tried to develop strengthening methods using notches and anchor bolts which could supply the defect on falling off of the plate at the end.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.04a
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• pp.703-708
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• 1999

The concrete structure under fatigue load depresses in mechanical capability or breaks down finally because of the fatigue. So recently the study on strengthening methods using bonded steel plate is widely attended. Which could be constructed under use and without damaging the structure. The intention of this method is to increase the useability of the structure and to recover the strength. So application on fields are sharply increasing. In this study it is tried to develop strengthening methods using notches and anchor bolts which could supply the defect on falling off of the steel plate at the end.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.1
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• pp.304-314
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• 2016

This study was conducted to understand the meaning and nature of the compassion fatigue experiences among nurses working in oncology wards. The participants in this study were 11 nurses who worked for at least 6 months in oncology wards. The data were collected using in-depth interviews and analyzed using the phenomenological method by Giorgi. Six categories of the meaning of compassion fatigue were derived as follows; physically difficulty, emotion is control of patient's condition, collapsing in front of cancer patients, reminding of patient-related memory, finding a changed attitude, and searching for how to recover.

• Journal of Life Science
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• v.8 no.3
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• pp.241-248
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• 1998

In an attempt to investigate the effects of Samultang, Samultang-Mixed-Kamibulhwangumjungkisan extract on the ability of rat to recover from exhaustion after severe exercise. The results are as follows 1. Lactate was found to show remarkable decrease in the rat with administration of Samultang-Mixed-Kamibulhwangumjungkisan group at 120 min (p<0.001). 2. LDH showed elevation in the rat with administration of Samultang-Mixed-Kamibulhwangumjungkisan group 120 min.(p<0.05) 3. Glucose showed elevation in the rat with administration of Samultang-Mixed-Kamibulhwangumjungkisan group at 120 min.(p<0.05) 4. FFA showed decrease in the rat with adminstration of Samultang-Mixed-Kamibulhwangumjungkisan hroup at 120min.(p<0.05) From these results, we recoginized that the effects of Samul-tangmixedKamiBulhwangumjungkisan group is better than Samultang group on the recovery of exercise induced fatigue.

• Child Health Nursing Research
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• v.12 no.2
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• pp.196-203
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• 2006

Objectives: This study was conducted to test whether stretching helps high school students recover from their fatigue and improve concentration. Method: The method of this study adopted a nonequivalent control group with pre-test and post-test designs. The period of data collection was from November to December in 2004. The 135 subjects were randomly selected from two high schools in Ulsan : one school as control group(n=66) and the other school as an experimental group(n=69). The experimental group had stretching for 10 minutes before the start of their fifth period class, five times a week(once a day) 4weeks of period, but the control group did not do. Result: After stretching, the students' level of fatigue in the experiment group was immensely reduced (t=4.75, p<.001). After the stretching, the concentration level of the experimental group increased vastly compared to the control group (t=3.35, p≤.005). Conclusion: Stretching is useful to reduce fatigue and improve concentration of high school students. This study recommended that stretching, which is not limited by high physical techniques, or specific time or spaces would help high school students' health, since they do not exercise regularly and are tired physically and mentally.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.31 no.1
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• pp.43-56
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• 2023

The aviation industry has continued to grow despite the influence of external environmental factors such as SARS and MERS. However, this growth has led to a sharp decrease in air traffic and a crisis of flight suspension due to the collapse of the global value chain and the decline of the world economy as the World Health Organization (WHO) declared a COVID-19 pandemic. Due to the decrease in the number of international flights, aviation workers such as pilots and cabin crew were exposed to high psychological stress and fatigue, such as large-scale layoffs, job instability, decrease in income, and increased risk of infection during. Recently, the international community has eased immigration restrictions through quarantine activities, and airlines are taking a step further to recover existing air demand. However, during the crisis period, a significant number of professional workers have been turned off or fired, and the physical and mental fatigue of those who can perform their duties is increasing. Therefore, this paper intends to examine the direction of policy improvement and the identification of problems in aviation safety and fatigue management after the pandemic.

• Tribology and Lubricants
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• v.30 no.6
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• pp.350-355
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• 2014

This study proposes a sustainable bearing remanufacturing process using the ultrasonic nanocrystal surface modification (UNSM) technique. The UNSM technique is a newly developed and sophisticated surface modification technique that can increase the mechanical properties and improve the friction and wear performance of materials. Taking advantage of the bearing manufacturing process is the most significant way of optimizing the life of a bearing. The proper maintenance and usage of repaired bearings can increase their life to be equal to or greater than that of new bearings. This paper discusses the restoration of certain mechanical properties of worn, damaged, and discarded bearings, and suggests a remanufacturing process for used bearings, which can impart them with a lifespan equivalent to that of new bearings. The most damaged part of the discarded bearings is the raceway, which is the site of accumulated fatigue. The existing polishing or barrel finishing processes can recover the accumulated fatigue only partially. Rolling contact fatigue tests performed on UNSM-treated new and used specimens polished after $4{\times}10^6$ cycles reveal that UNSM-treated new specimens exhibit the longest fatigue life compared to other specimens. This study verifies the proposed complete fatigue recovery process, which can increase the fatigue life of used bearings to a level greater than that of new bearings.